Probiotics and Antimicrobial Proteins最新文献

This study aimed to isolate and identify a fiber-degrading probiotic strain from traditional yak yogurt on the Qinghai-Tibet Plateau and evaluate its effects on rumen fermentation and microbial metabolism. Through carboxymethyl cellulose (CMC) screening, filter paper degradation, and straw degradation tests, a lactic acid bacterium-Pediococcus pentosaceus JASB0677-was obtained, with a straw degradation rate of 18.74%. P. pentosaceus JASB0677 exhibited tolerance to simulated gastric (pH 3.0, 1% pepsin, survival rate: 69.01%) and intestinal juices (pH 8.0, 1% trypsin, 63.18%) and showed bile salt resistance at 0.1%, 0.2%, and 0.3% concentrations (survival rates: 79.05%, 63.34%, and 52.32%, respectively). It also demonstrated strong antibacterial activity, with an inhibition zone diameter of 20.03 mm against Salmonella, and antioxidant activity, with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rates of 46.52% and 39.17%, respectively. In vitro rumen fermentation revealed that P. pentosaceus JASB0677 significantly increased acetate and total volatile fatty acids (TVFAs) concentrations while reducing ammonia nitrogen levels (p < 0.05). 16 S rRNA sequencing revealed that P. pentosaceus JASB0677 altered the rumen microbial composition by increasing the relative abundance of Proteobacteria, Actinobacteria, Enterobacter, Klebsiella, and Christensenellaceae_R-7_group. Metabolomic analysis revealed significant modulation of several metabolic pathways, especially those related to amino acid and lipid metabolism. Correlation analysis indicated that acetate and TVFAs concentrations were significantly positively correlated with the abundances of Proteobacteria, Actinobacteria, Enterobacter, and Klebsiella, as well as specific metabolites including mevalonic acid and L-leucine, while ammonia nitrogen showed the opposite trend (p < 0.05). These results suggest that P. pentosaceus JASB0677 is a promising candidate functional feed additive for enhancing fiber utilization, maintaining microbial homeostasis, and improving rumen fermentation in ruminants.

A 56-day feeding trial was conducted to compare the effects of pomelo peel and soybean meal (SM) fermented by microorganisms alone (BFPS) or in combination with enzymes (EBFPS) on growth performance, serum biochemistry, and intestinal health of large yellow croaker (Larimichthys crocea). Large yellow croaker was randomly assigned to three groups (C, BFPS, and EBFPS) with four replicates per group and 160 fish per replicate. Results showed that BFPS and EBFPS significantly improved the growth performance and feed utilization. Fish fed BFPS- and EBFPS-containing diets exhibited reduced hepatosomatic index and serum activities of aspartate transaminase and alanine transferase, indicating superior liver health. Additionally, dietary BFPS and EBFPS increased serum lysozyme activity and immunoglobulin M concentration, while significant enhancement of serum alkaline phosphatase and acid phosphatase activities was only observed in the EBFPS group. Improvements of mid-intestinal morphology in BFPS and EBFPS groups were accompanied by reduced serum diamine oxidase activity and D-lactate content, as well as up-regulated expression of tight junction-related genes (zo-1, claudin-11, and occludin) in the mid-intestine. Interestingly, BFPS was associated with suppressed mid-intestinal inflammation and activated toll-like receptor (TLR) signaling, whereas EBFPS induced moderate inflammatory responses and down-regulated TLR signaling. The results of mid-intestinal microbiota showed that compared with C and BFPS groups, croakers fed the EBFPS diet exhibited a higher Shannon index and distinct community structures. Moreover, BFPS led to reducing mid-intestinal Brevinema but sharply increased Desulfobacterota, Lawsonia and Pseudomonas abundances, while EBFPS decreased Desulfobacterota, Lawsonia and Brevinema and increased unclassified_Bacteria. Overall, both BFPS and EBFPS positively modulated growth performance and mid-intestinal health, with distinct effects on immune responses and microbial community composition in large yellow croaker (L. crocea).

This study aimed to characterize the microbial composition of green tea-fermented kombucha at different fermentation times and to evaluate its effects on inflammation and alveolar bone loss in rats with periodontitis. Microbial diversity was first assessed by metagenomic sequencing targeting bacterial 16 S rRNA and fungal 18 S rRNA regions. Sixty male rats were divided into six groups: control, periodontitis without treatment, green tea treatment, and kombucha fermented for 4, 8, or 12 days. Kombucha or green tea was administered daily by oral gavage for 39 days. Periodontitis was induced by ligation of the maxillary second molar on day 28. After euthanasia, hemimaxillae, liver, kidney, and blood samples were collected for analysis. Kombucha fermented for 4 days showed the highest abundance of bacteria from the Acetobacteraceae family and yeasts from the Saccharomycetaceae family. This fermentation time also produced the most pronounced reduction in periodontal inflammation and alveolar bone loss, with lower expression of tumor necrosis factor-alpha (42,9%) and receptor activator of nuclear factor kappa-B (43,6%), as well as higher expression of osteoprotegerin (approximately 55,4%) in periodontal tissues compared to animals with periodontitis without treatment. Notably, kombucha did not induce renal or hepatic toxicity regardless of fermentation time. These findings suggest that kombucha, particularly after 4 days of fermentation, reduces inflammation and alveolar bone loss without systemic toxicity, supporting its potential as an adjunctive therapy for periodontitis.

Neonatal sepsis continues to pose rising critical challenges to global health, particularly in low and middle-income countries, where it accounts for a substantial proportion of neonatal morbidity and mortality. The increasing prevalence of multidrug-resistant (MDR) pathogens in neonatal sepsis has significantly weakened the efficacy of conventional antibiotics, necessitating urgent exploration of alternative antimicrobial therapies for better clinical outcomes. Emerging research interest is growing to develop the microbial-derived peptides as novel antimicrobial agents, particularly "bacteriocins." In comparison to traditional antibiotics, many bacteriocins exhibit narrow-spectrum action, enabling them to inhibit specific pathogens without disrupting the host microbiota. Recent studies have highlighted the remarkable potential of lactic acid bacteria (LAB) derived bacteriocins in combating MDR pathogens responsible for neonatal sepsis. In this review, we compile current literature on the in vitro antimicrobial activity of LAB-derived bacteriocins, molecular diversity, mechanisms of action and clinical potential. Special attention is given to bacteriocins produced by LAB associated with the milk-derived microbiota, whose natural protective functions could be particularly beneficial for immunocompromised newborns. Additionally, we discuss the physicochemical properties of microbial peptides, including thermal stability, enzymatic resistance, and pH tolerance, which support their suitability for pharmaceutical applications. Overall, LAB-derived bacteriocins represent a novel, biocompatible, and complementary antimicrobial strategy integrated with conventional antibiotics to fight against MDR in neonatal sepsis. Further research and multicentric clinical trials are necessary to fully explore its compliance and efficacy as a future antimicrobial agent in neonatal medicine to underscore their potential as adjunct or preventive biotherapeutics in NICU settings.

Gassericins K7 are heterodimeric bacteriocins produced by Lactobacillus paragasseri K7. Their biological characterisation has been limited by challenges in obtaining these compounds in sufficient purity and quantity. In this study, we used a preparative isolation and purification workflow for gassericins K7, combining ammonium sulphate precipitation, Amberlite XAD-16 extraction, and reversed-phase chromatography. Mass spectrometry confirmed the presence of all four peptide components GasK7A α, GasK7A β, GasK7B α, and GasK7B β in the pooled preparation, including GasK7A β, identified here for the first time in natural isolates of this strain. The purified bacteriocin preparation exhibited strong antibacterial activity against indicator strain Latilactobacillus sakei NCDO 2714. Cytotoxicity testing in RAW 264.7 macrophages revealed minimal effects at concentrations up to 50 µg/ml, with only a modest reduction in cell viability observed at 100 µg/ml. Subsequent evaluation of immunomodulatory properties demonstrated a clear dose-dependent anti-inflammatory effect in LPS-stimulated macrophages. Treatment with gassericins K7 reduced nitric oxide (NO) production, downregulated inducible nitric oxide synthase (iNOS) expression, and suppressed secretion of the pro-inflammatory cytokines TNF-α and IL-6. Importantly, exposure of macrophages to gassericins alone did not elicit any inflammatory response. These findings provide the first evidence of anti-inflammatory activity of purified gassericins K7 in eukaryotic immune cells and highlight their potential as postbiotic components or biotherapeutic candidates for inflammatory disorders. The preparative method used in this study enables the production of gassericins K7 in quantities sufficient for advanced in vitro and in vivo investigations, facilitating future development of bacteriocin-based therapeutics.

Antibiotics are frequently used in livestock, aquaculture, and poultry, resulting in their accumulation in these animals and the surrounding environment. This contamination can present health risks to humans. Research on the harmful effects of antibiotics, especially their potential to disrupt hormones in the male reproductive system, is still in its early phases. This study investigated the impact of exposure to the antibiotic amoxicillin (AMO) on male reproductive health. The aim is to shed light on the potential dangers antibiotics pose to male reproductive health and to emphasize how Bacillus clausii may help protect against the toxic effects of AMO. The study included four groups treated via gavage: control animals, a supplemented group receiving B. clausii (1.25 ml, 1 × 10^9 CFU per mouse per day), a group treated with AMO at 30 mg/kg daily, and a fourth group that received AMO and B. clausii. After 45 days of treatment, blood samples were collected to assess serum activities of superoxide dismutase and catalase and levels of reduced glutathione, malondialdehyde, and testosterone. Testicular tissue samples were analyzed for mechanistic target of rapamycin (mTOR) gene expression and histological changes. This study demonstrates that exposure to AMO negatively impacts male reproductive health by increasing oxidative stress, reducing testosterone levels, causing testicular damage, and downregulating the mTOR expression level. However, supplementation with B. clausii mitigates these harmful effects, likely due to its antioxidant properties. The probiotic reduced oxidative stress markers, improved testosterone levels, and alleviated testicular lesions, thereby upregulating the mTOR expression level, which suggests its potential protective role against antibiotic-induced toxicity.